Is daily CT image guidance necessary for nasal cavity and nasopharyngeal radiotherapy: an investigation based on helical tomotherapy.

ABSTRACT: In order to analyze the magnitude of set up errors corrected by Helical TomoTherapy Mega-Voltage CT on a daily or weekly basis and their impact on the delivered dose to the tumor and organs at risk (OAR), the setup errors of 6 nasal cavity and 4 nasopharyngeal cancer patients who were treated with Helical Tomotherapy for 25-33 fractions were retrospectively analyzed. Each patient had MVCT guided repositioning for all fractions of treatment. The new dose volume histogram (DVH) and equivalent uniform dose (EUD) for planning target volume (PTV) and OARs were calculated for hypothetical situations where no imaging guidance (IG) or once weekly image guidance (WIG) took place. The mean total set up error if treated without daily IG was 3.6+/-1.0 mm, which can be reduced to 1.7+/-0.6 mm if a WIG

SUBMITTER: Sheng K 

PROVIDER: S-EPMC5721532 | biostudies-literature | 2008 Jan

REPOSITORIES: biostudies-literature